This about alpha-thalassemia is correct

The correct option is All of the above.

To understand why all the given statements are correct, let us analyze each of them step-by-step:

1. Haemoglobin fails to produce enough alpha protein in alpha-thalassemia:
Hemoglobin is the iron-containing oxygen-transport metalloprotein in red blood cells. Normal adult hemoglobin (HbA) is a tetramer consisting of two alpha (α) globin chains and two beta (β) globin chains. Alpha-thalassemia is a genetic blood disorder characterized by a reduced or completely absent synthesis of alpha-globin chains, which means the body fails to produce enough alpha protein subunits for hemoglobin.

2. Number of gene mutations decide the severity of the condition:
The synthesis of alpha-globin chains is controlled by four genes (two on each chromosome 16). The severity of alpha-thalassemia depends directly on how many of these four genes are mutated or deleted:
- One mutated/deleted gene: Silent carrier state (asymptomatic).
- Two mutated/deleted genes: Alpha-thalassemia trait/minor (mild anemia).
- Three mutated/deleted genes: Hemoglobin H disease (moderate to severe anemia).
- Four mutated/deleted genes: Alpha-thalassemia major or Hydrops fetalis (fatal before or shortly after birth).

3. Alpha-thalassemia is common in South-east Asia, southern Asia, India etc:
Alpha-thalassemia is geographically prevalent in regions where malaria is or was endemic, as carriers of the trait enjoy a selective survival advantage against malaria. Consequently, it is highly common in South-east Asia, southern Asia, the Middle East, India, and parts of Africa and the Mediterranean.

Since all three individual statements are correct, the choice "All of the above" is the correct answer.